Weld-electrode and product



Aug. 13, 1957 F. K. BLOOM 2,802,755

WELD-ELECTRODE AND PRODUCT Original Filed April 2, 1947 V Ni maiden/aleto 5.5%

Mn incidenfa/s to /4.6'%

Iran remainder; with INVENTQR Fredric/r K. Bloom ATTORNEY United StatesPatent WELD-ELECTRODE AND PRODUCT 738,948, April 2, application January21, 1953, Serial No.

Continuation of application SerialNo.

1947. This 332,531

3 Claims. 31. 117-207 g i This application is a continuation of myapplication Serial No. 738,948, filed April 2, 1947, andentitledElectrode and Deposit, now abandoned, and the invention relatesto deposit welding,more particularly to an art and manufactures forproducing corrosion-resistant hard facings and hard faced products, andto the faced products themselves.

An object of my invention is the provision of hardfacing rods orelectrodes which are readily produced and have Well balanced ingredientsfor giving highly satisfactory stainless steel hard-facing weld depositswhich are hard as deposited. i

A further object is that of providing a simple, direct and thoroughlypractical method which is effective and reliable for giving durable,substantially crack-free hardfacing weld deposits.

A still further object of my invention is the provision of hard-facedmetal products, asfor example those including a carbon steel base, whichare highly resistant to corrosion, abrasion and heat, and aresubstantially free of cracks in the hard facing.

Other objects in part will be obvious and in part pointed outhereinafter.

The invention accordingly consists in the combination and proportionmentof elements, composition of materials, and features of construction, andin the several steps and the relation of each of the same to one or moreof the others as described herein, the scope of the application of whichis indicated in the claims at the end of this specification.

'As conducive to a clearer understanding of certain features of myinvention it may be noted at thispoint that deposit welding includes theart of thermally fusing onto a suitable metallic base such as onto oldor new carbon steel parts which are to be protected against wear, facingof another metal, as for example a, thermally deposited surface, edge,point, or the like better suited for serving desired functions than theunderneath metal. These facings achieved by deposit surfacing or weldingoperations, under certain circumstances represent an easy and economicalmeans for keeping equipment in good operating condition and free ofoften repeated shut-down for repair or replacement, of parts. When of ahard quality, the facings are in demand for serving any of a widevariety of functions as where requirements include resistance toabrasion. Hard facings originally were introduced on such products asmetal working dies, oil well drilling tools, certain types of excavatingequipment, and the like, but additional uses soon were found, so thatnow the art of hard deposit surfacing is an important factor involved inmany production and maintenance techniques, and in a large variety ofspecific industries and products.

A great number of the theretofore known hard facings, however, aresusceptible to corrosion, the rate being so detrimental where corrosiveatmospheres, liquids or solids are encountered that initial cost ofincluding the facing on a particular product cannot bejustified. Afurther difiiculty arises in the prior art where during formation ofhard facings by deposit welding, the metal has a strong tendency tocrack at the interface made with the base metal or between depositedbeads of the Weld. These detriments too frequently arise by reason ofparticular composition of the deposited metal. Some of the facings arehighly susceptible to cracking because of hot-short ness, this tooreverting back to composition of the deposit. The occurrence. ofcracking usually is responsible for losses in production, often callsfor costly replacement of parts because of failure or inadequacy of thecracked hard facing metal, and even becomes so objectionable as torender further'use of 'a given welding composition undesirable fordeposit facing purposes.

The question of hardness frequently is a controlling factor with regardto utility of a hard faced article or product; this is particularly sowhere resistance to abrasion or scour is of considerable importance. Itfollows, however, that certain of the prior art hard facing materialsserve well when exposed to wearing and abrading influences, but fail fartoo readily where usage includes exposure.

An outstanding object of my invention accordingly is the provision ofstainless steel hard-facing rods or electrodes which are easily producedas from the standpoint of producing the metal thereof and working thesame to desired shape, and which rods and electrodes give strong, hardfacings further having resistance to corrosion and abrasion andsubstantial freedom from cracking.

Referring now more particularly to the practice of my invention, Iprovide hard faced metal products of which the facing is a substantiallyfully martensitic, strong, durable and crack-resistant stainless steel,deposited by thermal fusion. I find advantage in employing a weld rod,illustratively an electrode, having the constituents thereof soproportioned as to melt down and produce the facing, after which thedeposit takes on a high hardness or hard set immediately upon cooling inair or by otherwise quenching from the depositing temperature. Althoughsubstantially martensitic, the facing also includes small amounts ofretained austenite which increase ductility and crack-resistance. Smallamounts of ferrite usually are present, this without destroying theproperty of high hardness. The metal underlying the facing preferably isa plain carbon steel as for example of low, medium or even high carbongrade.

Because of losses which sometimes occur in deposit welding or facingoperations and because of other variables, the composition of the facingrod or electrode which I provide is given in terms of the hard facingdesirably obtained. The rod or electrode is of such com? position as toyield a stainless steel hard facing deposit, comprising about 10% to 22%chromium, nickel from small and fractional percentages under 1% andranging up to about 5%, from small or incidental amounts up toapproximately 10% manganese, about 0.10% to 0.90% carbon, and theremainder substantially all iron. At the same time, however, I restrictthe amounts of chro mium, nickel, manganese and carbon in the rod .toamounts which ensure that the ratio or relationship of these elements inthe hard facing obtained is substantially consistent with the terms ofthe following empirical formula: Percent Cr (Percent. Ni+ 10 (Percent(3)) =a numerical value ranging up to approximately maximum, orpreferably a numerical value between about 50 and 90. Where the maximumnumerical value in the formula is exceeded, the high hardness achievedimmediately with cooling the facing from deposit temperature suffers.

The welding rod preferably includes a coated stainless 2,802,755 i r r rV V a steel wire or powdered metal core having contents of the core andcoating sufiicient in view of possible losses while forming the deposit,to give hard facings having a composition of the character hereinbeforedescribed which satisfies the formula. I find considerable advantage inmaking the core from any one of the standard type stainless steels notedbelow in Table I, any of these steels being readily provided andillustratively, not' worked to desired size and shape.

I coat the metal core with a mineral flux, as by continuously feedingthe metal through a suitable fluxextruding die and extruding on theflux. The flux coating preferably is substantially free ofhydrogen-yielding constituents, and illustratively includes a dehydratedmineral slag-forming material having a composition of the character moreparticularly set forth in the copending George E. Linnert application,Serial No. 565,573, filed November 28, 1944, now U. S. Letters PatentNo. 2,544,334 of March 6, 1951. For building up the rod composition, Isometimes add amounts of any needed elements to the coating, as forexample manganese in the form of powderedferromanganese or chromium inthe form of chromium ferroalloy. Nickel is added as nickel powder andsometimes as nickel oxide. Powdered graphite sometimes is introduced inthe coating as a source of carbon. These materials conveniently areapplied in mixture with the flux to the core. At times, the coating issubstantially all flux, the core for example in this instance being theentire source of metal.

With reasonably good protection from oxidation the recoveries which canbe expected of the various alloy ingredients referred to above are asfollows: Carbon, 75%; chrominum, 95 nickel, 100%; manganese, 75%.Calculation, therefore, reveals that with an average dilution by thebase metal of about 25% the rod or electrode composition, including coreand coating, comprises about 11.6% to 25.6% chromium, nickel from smalland fractional percentages under 1% and ranging up to about 5.5%, fromsmall or incidental amounts up to approximately 14.6% manganese, about0.15% to 1 .30% carbon, and the remainder substantially all iron. At thesame time, the amounts of chromium,

nickel, manganese and carbon in the rod are further restricted toamounts that asssure that the ratio or relationship of these elements inthe hard face obtained is V substantially consistent with the empiricalformula given TABLE I Stainless steel core compositions Stand- Percentard bi 0 Or N1 Mn S1 S P 410-.-" 0.15 11. 50l3. 50 1.00 l. 00 0.04 0.04Max. ax Max Max. Max. 414"-.. 0.15 11. 50-13. 50 1. 25-2. 50 1 00 1. 000; 04 0.04 3 Max. Max. Max. Max. Max. 420..-.- 0. 15 12. 00-14. 00 1.00 1. 00 0. 04 0.04 Min. Max. Max. Max. Max. 430-..-. 0. 12 14. 00-18.00 1. 00 1.00 0. 04 0. 04 Max. Max Max Max. Max. 431-.-" 0.2015.00-17.00 1.25-2.50 1.00 1. 00 0.04 0.04

Max. Max. Max. Max. Max. 440A 0.60-0.75 16. 0018.00 1. 00 1.00 0.04 0.047 Max. Max. Max. Max. 442.--... 0.35 18.00-23.00 1. 00 1.00 0.04 0.04Max. Max. Max. Max. Max.

faced products which I achieve are numerous.

They gain a martensitic structure and high hardness with cooling in airor otherwise quenching from the temperature used for depositing. Theparticular combination of ingredients which I employ in depositing thefused-on stainless steel facing further ensures a considerable,resistance, by the deposited metal to cracking at the interface with theunderneath metal as for example at the interface witha mild steel base.As a matter of still further importance thefacing, where produced 'bydepositing b'eads of the stainless steel as by electric arc weldingmethods, resists cracking at the points of interbeading and also resistscracking in use when hotjor cold. I usually maintain'a minimum ofsuchresidual elements as sulphur and phosphorus in thefelectrode and in thefacing obtained; for enhancing the resistance to cracking. Thedehydrated mineral flux which I prefer to use, also contributes tofreedom from cracking. My stainless, steel hard facings. resist wear,abrasion; and

corrosion under. a wide variety of conditions. They are.

strong, hard, tough and durable. 1

The uses for the stainless steel hard facings and hard A large numberof. uses are satisfactorily served where the hard faced products areexposed to heavy wear or continuous abrasion, particularly in locationswhere exposure to moisture, damp air, chemicals, gases and othercorrosive' substances are encountered, .or where frequent replacement ofmachinery parts would be expensive and uneconomical. Several of my hardfaced products are gears, pinions, slides and guides for machinery suchas engines handling gritty, sandy, sharpores and earths, as in min ingmachinery where severe abrasion and acid or chemical-ladenwa ters areencountered. I also produce hard faced products (for example parts forsuction dredges and pumps) which are useful where high velocity liquidsladen with solids are contacted. In certain instances the produc-tswhich I achieve fall into a class affording prolonged life, and wherethe life is extended indefinitely by renewing the stainless steelhardfacing from time to time. Other products are scrapers, cylinders andteeth for grain separators, plow shares for sandy or gritty soil, dragchains, cam and screw machine parts, aeroplane tail. skids, Vises, dies,tongs, and similar seizing and holding equipment. There are of course avast number of. other products falling within the scope of the presentinvention, the above productsbeing noted for the sake of illustration.

As illustrative of the practice of my invention, I provide an arcwelding electrode having a core and a coating, in which electrode ormanufacture the carbon, chromium, manganese and nickel are present insuch amounts as to yield a deposited facing containing these elements inaccordance with any one of the compositions noted below in Table II orin any other proportions approximately. consistent. with thegeneralcomposition ranges, and formula hereinbefore setforth. The table applies.tohard facings which contain carbon, chromium,

substantially all iron.

- TABLE II Hard facing compositions Hard Facing Deposit Rockwell No.Formula Hard- Ratio ness of C Cr Ni Mn Deposit 0 11 15 51 1. 99 0.70 53C 42 0 24 15. 54 l. 99 0. 68 73 C 49 0. 12 15. 18 1. 83 3. 76 C 41 0 1615 25 1.83 3 71 79 O 42 The electrode or rod compositions employed toachieve the hard facing compositions of Table H are given below in TableIII TABLE HI Weld rod compositions In use, I fit the electrode intosuitable arc Welding equipment as for operation on direct current,reverse polarity. The amount of current used is for example in the rangeof 140 to 160 amperes. For best results the surface of the metal toreceive the deposit, is cleaned of all loose scale, dirt, rust or otherforeign substances, this by pickling, grinding, machining, wire brushingor the like. Then, by bead deposit welding or any other satisfactoryprocedure, I employ the electrode for building up a facing on the cleanmetal base such as on a pro-formed plain carbon steel or high alloysteel product. I deposit a sulficient amount of the metal and then hotfile and cold grind or otherwise work the same to desired dimensions.The facing upon cooling, immediately takes on a high hardness.

Hard facings of exceptionally durable and lasting quality are obtainedon products of high alloy or low alloy steel, or on other metals oralloys, through the use of my electrodes. Sometimes I deposit thefacings on hardening steels or even on hardened steels. Quite often themetal base receiving the facing is not materially responsive tohardening heat treatment, or for other reasons is the unhardeuedcondition when the hard faced products are put into use.

Thus it will be seen that in this invention there are provided a fusiblewelding rod as for example an electrode, a method of producing hardfacings and hard faced products, and the hard faced products themselves,in which the various objects noted herein together with many thoroughlypractical advantages are successfully achieved. It will be noted thatthe rods or, electrodes, are of such metallic contents as to givelasting stainless steel hard facings which are strong, resistant toabrasion and corrosion and also resistant to cracking.

As many possible embodiments may be made of my invention and as manychanges may be made in the embodiments hereinbefore set forth, it willbe understood that the matter described herein is to be interpreted asillustrative and not as a limitation.

I claim as my invention:

1. A hard facing electrode for the production of a facing which issubstantially fully martensitic as deposited comprising a metallic core,and a flux coating thereon,

said core and coating essentially consisting of about 11.6% to 25.6%chromium, incidental amounts up to about 5.5% nickel, incidental amountsup to about 14.6% manganese, about 0.15% to 1.30% carbon, with chromiumcontent exceeding the sum of the nickel and manganese contents and saidchromium, nickel, manganese and carbon being substantially consistentwith the empirical formula: percent chromium (percent nicke1|.38(percent manganese) +7.5 (percent carbon))=a numerical value rangingbetween 61 and 116, and the remainder substantially all Iron.

2. A hard facing electrode for the production of a facing which issubstantially fully martensitic as deposited comprising: a stainlesssteel core, and a dehydrated mineral flux coating on the core, said coreand coating essentially consisting of about 11.6% to 25.6% chromium,nickel up to about 5.5%, manganese up to about 14.6%, carbon about 0.15%to 1.30%, with the chromium content exceeding the sum of the nickel andmanganese contents and with the chromium, nickel, manganese and carbonall in relationship substantially consistent with the empirical formula:percent chromium (percent nickel+.38 (percent manganese)+7.5 (percentcarbon) )=a numerical value ranging between 61 and 110 and the remaindersubstantially all iron.

3. A hard facing electrode for the production of a facing which issubstantially fully martensitic as deposited comprising: a hot-workedstainless steel core, and a flux coating thereon, said core and coatingtogether essentially consisting of about 11.6 to 25.6 chromium, nickelup to about 5.5 manganese up to about 14.6%, carbon about 0.15 to 1.30%,with the chromium content exceeding the sum of the nickel and manganesecontents and with the chromium, nickel, manganese and carbon all inrelationship substantially consistent with the empirical formula:percent chromium (percent nickel+.38 (percent manganese)+7.5 (percentcarbon) =a numerical value ranging between 61 and 110 and the remaindersubstantially I all iron.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Welding Metallurgy, 2nd edition (American Welding Society,1949), pp. 392-400.

1. A HARD FACING ELECTRODE FOR THE PRODUCTION OF A FACING WHICH ISSUBSTANTIALLY FULLY MARTENSITIC AS DEPOSITED COMPRISING A METALLIC CORE,AND A FLUX COATING THEREON, SAID CORE AND COATING ESSENTIALLY CONSISTINGOF ABOUT 11.6% TO 25.6% CHROMIUM, INCIDENTAL AMOUNTS UP TO ABOUT 5.5%NICKEL, INCIDENTAL AMOUNTS UP TO ABOUT 14.6% MANGANESE, ABOUT 0.15% TO1.30% CARBON, WITH CHROMIUM CONTENT EXCEEDING THE SUM OF THE NICKEL ANDMANGANESE CONTENTS AND SAID CHROMIUM, NICKEL, MANGANESE AND CARBON BEINGSUBSTANTIALLY CONSISTENT WITH THE EMPIRICAL FORMULA: PERCENTCHROMIUM(PERCENT NICKEL+38(PERCENT MANGANESE) +7.5(PERCENT CARBON) =ANUMERICAL VALUE RANGING BETWEEN 61 AND 116, AND THE REMAINDERSUBSTANTIALLY ALL IRON.